1. Field of the Invention
The present invention relates to a power breaking device that is arranged between a power source and an electric load thereby to connect the power source with the electric load through a fuse and also insulate the power source from the electric load by detaching the fuse. Particularly, the invention relates to a power breaking device which is attached on the side of a power source of an electric car and which is suitable for insulating the power from the load electrically.
2. Description of the Related Art
FIGS. 1 and 2 show a power breaking device 1 which is used in an electric car or the like and which is capable of insulating a power (battery) from a load (e.g. driving motor etc.) electrically. In the power breaking device 1, a pair of terminals 3 are disposed at a designated distance in a housing 2 made of insulating material. Connected to the terminals 3, 3 are respective ends of wires 4, 4 that extend to the exterior of the housing 2. The housing 2 is provided, on its upside, with an opening which can be closed by a cover 5 rotatably connected to one side of the housing 2. A fuse 6 is fixed on the back face of the cover 5 through a band 7.
On condition that the opening of the housing 2 is covered with the cover 5, respective terminals 8, 8 of the fuse 6 are connected to the terminals 3, 3 in the housing 2, respectively. In this state, since the terminals 3, 3 are connected to each other through the fuse 6, the wires 4, 4 are electrically connected to each other.
When the cover 5 is opened, the terminals 8, 8 of the fuse 6 are detached from the terminals 3, 3 or electrical disconnection, so that the wires 4, 4 are insulated from each other, certainly.
In case of using the so-constructed power breaking device in the electric car, when carrying out the maintenance work (inspection of circuits, change of fuses, etc.), it is possible to certainly insulate the power source from the load by only opening the cover 5, whereby the safety in operation can be ensured.
In the above-constructed power breaking device, however, it is impossible to properly connect the terminals 8, 8 of the fuse 6 to the terminals 3, 3 in the housing 2 due to the structure where the fuse 6 is fixed on the back side of the cover 5 rotatably attached to the housing 2. Therefore, when fixing the fuse 6 on the back side of the cover 5, it is necessary to position the fuse 6 precisely, raising a problem that enormous care and labor is required for exchanging the fuse 6.
In order to solve the problem, the applicant has proposed a power breaking device 16 shown in FIG. 3 (Japanese Unexamined Patent Publication No. 10-83753). In the device 16, a lever assembly 10 is provided with male terminals 11, 11 to which terminals 13, 13 of a fuse 12 are fixed by means of screws. While, a box part 14 is provided with 15 female terminals 15, 15. The connection between the male terminals 11, 11 and the female terminals 15, 15 is carried out while adjusting the lever assembly 10 to the box part 14.
In the power breaking device 16, the positioning of the lever assembly 10 against the box part 14 allows the male terminals 11 to be connected to the female terminals 15, 15 appropriately. Additionally, since the exchange of the fuse 12 is attained by only fixing the terminals 13, 13 of the fuse 12 to the male terminals 11, 11 by screws, there is no need of enormous care and labor in the exchange operation.
However, the above-mentioned power breaking device 16 also requires a structure for fitting the lever assembly 10 to a designated position on the box part 14, a structure for fixing the female terminals 15, 15 to designated positions in the box part 14 and a structure for fixing the terminals 13, 13 of the fuse 12 to the lever assembly 10. Therefore, the whole structure of the device 16 is complicated with an increased number of components.
Under such a circumstance, it is therefore an object of the present invention to provide a power breaking device which facilitates the exchanging operation of the fuse and which can be constructed by a reduced number of components owing to the device""s simple structure.
The object of the present invention described above can be accomplished by a power breaking device arranged between a power source and an electric load for connecting the power source with the electric load through a fuse and disconnecting the power source from the electric load by detachment of the fuse, the power breaking device comprising:
a stationary box provided, therein, with a power connection part connected to the power source and a load connection part connected to the electric load;
a fuse carrying box which is constructed so as to accommodate and retain the fuse therein, the fuse carrying box being detachably attached to the stationary box and also insulating the power source from the electric load when the fuse carrying box is detached from the stationary box; and
a guide and restricting mechanism for respectively guiding both terminals of the fuse into the power connection part and the load connection part while restricting the terminals movements on condition that the fuse carrying box is fitted to the stationary box.
Owing to the provision of the guide and restricting mechanism, it is possible to position the fuse with ease.
In the above-mentioned power breaking device, preferably, the stationary box comprises:
a fixed housing;
a load-side bus bar which is provided, on one end thereof, with a load-side terminal connected with the electric load and which is also provided, on the other end, with a first elastic connecting part for connection with one terminal of the fuse, the first elastic connecting part being retained in the fixed housing; and
a power-side bus bar which is provided, on one end thereof, with a power-side terminal connected with the power source and which is also provided, on the other end, with a second elastic connecting part for connection with the other terminal of the fuse, the second elastic connecting part being retained in the fixed housing.
According to the present invention, since the terminals of the fuse are directly connected to the first and second elastic connecting parts of the load-side bus bar and the power-side bus bar, it is possible to reduce the number of components.
In the power breaking device, more preferably, the fuse carrying box comprises:
a box body detachably mounted to the stationary box; and
a fuse fixing part arranged in the box body to accommodate the fuse therein.
In the power breaking device, more preferably, the guide and restricting mechanism is constructed so as to guide the connection of the respective terminals of the fuse with the first and second elastic connecting parts and also constructed so as to restrict the movements of the respective terminals of the fuse on condition that the terminals of the fuse are connected with the first and second elastic connecting parts, respectively.
In the power breaking device, more preferably, the guide and restricting mechanism comprises:
a partition wall formed integrally with the fixed housing to define an accommodating part for accommodating the fuse therein; and
a pair of slits formed in the partition wall;
whereby the respective terminals of the fuse are connected with the first and second elastic connecting parts since the respective terminals pass through the pair of slits.
In this case, when the fuse carrying box is fitted to the stationary box, the terminals of the fuse are introduced to the first and second elastic connecting parts through the slits. On condition that the terminals of the fuse are connected to the first and second elastic connecting parts, the movements of the terminals are restricted by respective inner walls of the slits.
In the power breaking device, more preferably, the fixed housing is provided with at least one guide rib which is positioned outside the fuse carrying box in engagement with the stationary box, thereby to restrict the deformation of the fuse carrying box.
When fitting the fuse carrying box to the stationary box, the movement of the fuse carrying box is guided by the guide rib in contact with the outer periphery of the fuse carrying box. Therefore, it is possible to fit the fuse carrying box to the stationary box with ease.
Now, providing that the fuse carrying box is separated from the stationary box for purpose of disconnecting the terminals of the fuse from the first and second elastic connecting parts, it may be expected that the fuse carrying box is deformed by resistance derived from the elastic connection between the terminals and the first and second elastic connecting parts. Nevertheless, according to the invention, the guide rib on the fixed housing operates to restrict the deformation of the fuse carrying box, Therefore, it is possible to detach the terminals of the fuse from the first and second elastic connecting parts while preventing the fuse from falling down from the fuse carrying box.
In the power breaking device, more preferably, the power breaking device further comprises a locking mechanism for locking the fuse carrying box in engagement with the stationary box, wherein the locking mechanism includes:
a pair of locking levers rotatably attached to both sides of the fuse carrying box in the longitudinal direction; and
a pair of engagement projections formed on the fixed housing for engagement with the locking levers.
In this case, when the locking levers are rotated to engage the engagement projections on condition of fitting the fuse carrying box to the stationary box, the resultant fitting condition can be maintained. When it is desired to separate the fuse carrying box from the stationary box, it is carried out to disengage the locking levers from the engagement projections. Consequently, the fuse carrying box can be detached from the stationary box with case. In connection, since the locking levers re rotatably attached to both sides of the fuse carrying box in the longitudinal direction, it is also expected to improve the efficiency in utilizing space in the neighborhood of the power breaking device.
These and other objects and features of the present invention will become more fully apparent from the following description and appended claims taken in conjunction with the accompany drawings.